1. Field of the Invention
This invention relates to an adaptor member for sharing an optical pickup between disc drive units having respective main axes and sub axes oppositely disposed and separated by different distances. The present invention also relates to disc drive units having respective main axes and sub axes oppositely disposed and separated by different distances and adapted to share a common optical pickup and a disc drive apparatus having such a disc drive unit.
2. Description of the Related Art
Optical discs such as CDs (compact discs) and DVDs (digital versatile discs) and magneto-optical discs such as MOs (magneto-optical discs) and MDs (mini discs) are known. A variety of disc drive apparatus have been marketed for such optical discs.
For example, referring to FIG. 1, a known disc drive unit 200 of a disc drive apparatus comprises an optical disc rotary drive mechanism 201 for driving an optical disc to rotate, an optical pickup 202 for carrying out an operation of writing signals onto or reading signals from an optical disc that is driven to rotate by the optical disc rotary drive mechanism 201 and a pickup feed mechanism 203 for driving and feeding the optical pickup 202 to move in a radial direction of the optical disc. The above listed components of the disc drive unit 200 are fitted to a base 204.
The disc rotary drive mechanism 201 includes a flat spindle motor 206 that is equipped with a turntable 205 for holding an optical disc. The spindle motor 206 drives the optical disc to rotate integrally with the turntable 205.
The optical pickup 202 writes signals onto or reads signals from the optical disc by converging the beam of light (laser beam) emitted from a semiconductor laser by means of an objective lens 207, irradiating the converged beam of light onto the signal recording surface of the optical disc and detecting the returning beam of light reflected by the signal recording surface of the optical disc by a photodetector.
The pickup feed mechanism 203 includes a pair of guide shafts 208a, 208b that support the optical pickup 202 so as to be movable in a radial direction of the optical disc, a rack member 209 fitted to the optical pickup 202, a lead screw 210 to be engaged with the rack member 209 and a stepping motor 211 for driving the lead screw 210 to rotate. As the stepping motor 211 drives the lead screw 210 to rotate, it consequently drives the rack member 209 that is engaged with the lead screw 210 to be displaced with the optical pickup 202 in a radial direction of the optical disc.
The base 204 has a table aperture 212a for exposing the turntable 205 and a pickup aperture 212b for exposing the optical pickup 202. The two apertures 212a, 212b are continued from each other. A number of components including the spindle motor 206, the opposite ends of the pair of guide shafts 208a, 208b, the lead screw 210 and the stepping motor 211 are fitted to the main surface of the disc drive unit that is opposite to the other main surface where the turntable 205 and the optical pickup 202 are exposed to the outside by way of the apertures 212a, 212b. 
In the disc drive apparatus that has the above described configuration and is adapted to record information signals onto or reproduce information signals from an optical disc, the disc rotary drive mechanism 201 drives the optical disc rotate and the pickup feed mechanism 203 drives and feeds the optical pickup 202 to move in a radial direction of the optical disc so that the optical pickup 202 operates for writing signals onto or reading signals from the optical disc. As a result, information signals are recorded onto or reproduced from the target recording tracks of the optical disc.
Meanwhile, the disc drive unit 200 having a configuration as described above is designed to be mounted in a very low profile disc drive apparatus, which very low profile disc drive apparatus is by turn to be mounted in a low profile host appliance such as a notebook-sized personal computer. In short, such a disc drive unit 200 is subjected to various restrictions in terms of its height. Additionally, the disc drive units 200 of disc drive apparatus that are marketed in these days are provided with an optical pickup 202 adapted to operate with discs of different recording formats such as CDs and DVDs. Optical pickups 202 adapted to operate with BDs (blue-ray discs) having a high density recording format are being developed.
Thus, the number of parts to be mounted in optical pickups 200 is ever increasing. Under these circumstances, there is a tendency of extending the width rather than the height of optical pickups 202 to be mounted in disc drive units 200 of the type under consideration in order to secure the space for mounting the parts. Then, the distance separating a pair of oppositely disposed guide shafts 208a, 208b for supporting the optical pickup 202 from each other is also increasing inevitably.
However, a disc drive unit 200 comprising a pair of oppositely disposed guide shafts 208a, 208b that are separated from each other by a large distance requires a new optical pickup 202 that matches the distance separating the pair of guide shafts 208a, 208b. In other words, a known disc drive apparatus requires the use of optical pickups 202 that are dedicated to respectively disc drive units 200 of different types.
In other words, it is not possible to share a single optical pickup 202 between two or more than two disc drive units 200 having respective pairs of guide shafts 208a, 208b separated by different distances in known disc drive apparatus to consequently give rise to a problem of high manufacturing cost. More specifically, if optical pickups 202 are prepared for disc drive units 200 of each type, dedicated metal molds are required for manufacturing such optical pickups to raise the manufacturing cost. Additionally, it is not possible to use common components and common manufacturing facilities to consequently raise the cost of managing components and that of replacing facilities.
Known published documents that relate to the present invention include Patent Document 1: Japanese Patent Application Laid-Open Publication No. 2002-25074. The Patent Document 1 describes an optical pickup apparatus having a base plate to which an attachment is fitted in order to make it possible to use a common optical base table for holding an objective lens and a lens drive section.